Monday, 20th—We continued our march northward today about ten miles, destroying six miles of railroad. All the railroads within twenty miles of Columbia have been destroyed, every tie is burned and every rail is twisted into a corkscrew. A sad accident happened yesterday afternoon in Columbia when a detail from the Fifteenth Army Corps was casting the fixed ammunition into the river. A man dropped a shell on the bank of the river, which exploding, caused other ammunition to explode and ignited a large quantity of powder, killing several soldiers and wounding twenty others. When Sherman heard of it, he is said to have remarked that one of his soldiers was worth more than all that ammunition or even the city of Columbia.